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Radio and Optical Observation of an Intense Flare on HD 32918

Published online by Cambridge University Press:  25 April 2016

John D. Bunton ,
M. I. Large ,
O. B. Slee ,
R. T. Stewart ,
R. D. Robinson  and
John D. Thatcher
John D. Bunton
Affiliation:
Department of Electrical Engineering, University of Sydney
M. I. Large
Affiliation:
School of Physics, University of Sydney
O. B. Slee
Affiliation:
Australia Telescope National Facility, CSIRO
R. T. Stewart
Affiliation:
Australia Telescope National Facility, CSIRO
R. D. Robinson
Affiliation:
Anglo-Australian Observatory
John D. Thatcher
Affiliation:
Anglo-Australian Observatory
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Abstract

During routine monitoring of active-chromosphere stars in August 1987 an intense radio flare on the FK Comae star HD 32918 was detected by the Parkes radiotelescope. Other observatories were notified, enabling data to be collected at 843 MHz, 1.4 GHz, 8.4 GHz and optical frequencies.

The flare at radio frequencies was largely similar to a previous event on this star, reaching a peak radio power of 5 < 1012 W Hz−1 at 8.4 GHz. During the flare the spectrum varied as ∼ v1.4 and later flattened as the flare progressed. Compared to the previous flare, circular polarization was higher.

Ca II and Hα optical spectra taken at the AAO 3.9-metre telescope show the star to have a highly active chromosphere and a strong wind, with a terminal velocity of ≈230 km s−1. While much of this activity appears to be long lived, there is good evidence for an increase in the strength of the chromospheric lines during the radio flare event.

Type
Stellar
Information
Publications of the Astronomical Society of Australia , Volume 8 , Issue 2 , 1989 , pp. 127 - 131
Copyright
Copyright © Astronomical Society of Australia 1989

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